Water Quality Evaluation of Aquifers Around Igboukwu and Environs , Southeastern Nigeria

he project area is located within Anambra State, Southeastern Nigeria and lies within latitudes 5°560 and 6°40N and longitude, 7°00 and 7°100E, encompassing Aguata, Aniocha and Orumba Local Government Area. These areas hydrologically fallwithin the Anambra Basin and more specifically within the Anambra River Basin (Fig. 1). The area hasabundant surface water and groundwater resources. The main river systems in the study areas are Odo, Obizi, Otalulu, Iyiagu and Uchu.

Benin hinge-line through the Onitsha high.The basin is about 300km long in a northern southwest direction, extending between the Onitsha and environs in Anambra State and Lokoja area in Benue State.Its southwestern extreme is about 48km wide (Whiteman, 1982) (fig.1).The stratigraphic succession in the Anambra Basin and environs have been discussed (Reyment, 1965;Whiteman, 1982;Hoque and Nwajide, 1984).A generalized geologic map of the basin adapted from the geological map of Nigeria by the Geological Survey of Nigeria (1974) is as shown in fig. 2. The geologic cross section shows that the study area is underlain by the Ameki Formation and the Imo Shale.The population here gets its water supplies from boreholes that tap from these two formations as well as from springs and streams.(Egboka et al, 1993).The study area has an undulating topography, with a maximum elevation of 300m above sea level and a minimum elevation of 100m above sea level.The major surface water body found in the study area is the Orashi River.Other surface waters in the area include otalulu, Uchu, Odor, Streams and the Obizi spring at Ekwulimi.Perennial and seasonal streams, springs drain the area.
There is connectivity existing between surface water systems and groundwater systems; the groundwater systems are recharged as a result of infiltration of parts of overland flow into the soil (Fetter, 2001;Heath, 1983).Figure 3 showed the drainage and location of the study area.

Climate and Vegetation
The study area lies within the humid tropical rain climate of Nigeria, with rainfall amounting to 2000mm per annum.In Aguata, the average annual temperature is 25.7°C and an annual average rainfall of 1975 mm (Fig. 4).The area experiences two Climatic seasons; the rainy season (March to October) and the dry season (October to March).These seasons have variable regimes.The dry season has the coldest, direst windy period known as the harmathan between November and February.The rainy season has its peaks in July and September with a dip in August known as "the August break".Much rainfall occurs as violent downpours, accompanied by lightning and thunderstorms, heavy flooding, soil leaching, sheet out wash and ground water infiltration and percolation.Minimum temperature is 23°C, maximum temperature is 34°C while the average temperature 28°C.Relative humidity is 80% during the raining season and 65% during the dry season (Okpoko, 1986).The driest month is December, with 11 mm of rain.The greatest amount of precipitation occurs in September, with an average of 318 mm.March is the warmest month of the year.The temperature in average is 27.4°C.The lowest average temperatures in the year occur in August, when it is around 24.0°C.There is a difference of 307 mm of precipitation between the driest and wettest months.The variation in temperatures throughout the year is 3.4 °C.The vegetation is characteristics of the humid tropical rainforest belt type of Nigeria, with trees, evergreen leaves and thick undergrowth.The vegetation cover has greatly reduced to Savannah type.It is characterized by open vegetative lowland interspersed with tall oil palm trees and deciduous trees.Agriculture practices are intensive, particularly along the hill slopes, dry river valleys and low-lying plains.These, further, reduce the vegetation to the aforesaid Savannah type.In some places, the vegetation has been cleared for agriculture, road construction, industrial sites and urban development.

MATERIALS AND METHODS
In order to achieve the goals of this research, the materials and methods used were; topographic map of the area on scales of 1:100,000, 1:250,000 and 1:500,000, global positioning system (GPS), plastic containers, generating set, and water depth well sounder.
During standard pumping tests, twenty borehole water samples were collected for geochemical analysis.All the collected samples were carefully labeled according to the respective locations and put in an ice packed bag.The samples where properly labeled indicating the time of collection.

RESULTS AND DATA ANALYSES
Water quality was assessed using physical, chemical and biological parameters.The physical parameters investigated include appearance, temperature, colour, odour and turbidity.The chemical parameter investigated include pH, conductivity, total dissolve solids, salinity, copper, nitrite, manganese and the major cations and anions.The bacteriological parameters investigated were for fecal coliform count and total coliform.The results were presented in Tables 1 and 2. All investigations/assessment were carried out using standard recommended methodologies and interpreted against World Health Organization (WHO, 2001) and Nigeria Standard for Drinking Water Quality, recommendations/guidelines (NSDWQ, 2007).Statistical methods were used to obtain the mean, range, variance and standard deviation for the pH and major anions and cations found in water samples of the study area.The mean pH is 5.8 with range of 0.8, variance of 0.07 and standard deviation of 0.26.The mean value for conductivity is 67.13uS/cm, range is 104.9uS/cm,variance is 844uS/cm and standard deviation is 29.1uS/cm.Calcium and Magnesium ions gave mean values of 2.4mg/l and 15.8mg/l, range of 33mg/l and 21mg/l, variance of 87.3mg/l and 39.3mg/l and standard deviation of 9.3mg/l and 6.3mg/l respectively.The mean value for sodium is 22.0262mg/l, range is 28.842mg/l, variance is 70.8215mg/l and standard deviation of 8.4mg/l.Potassium value is 8.83mg/l for mean, 8.29mg/l for range, 5.5099mg/l for variance and 2.3mg/l for standard deviation.The Ca ++ Mg++, Na+ and K+cations analysed fall within the recommended standard for potable water World Health Organisation (WHO), 2006.The mean sulfate concentration is 1.75mg/l range is 6mg/l, variance is 2.7mg/l and standard deviation is 1.6mg/l.Chloride value for mean is 4.99mg/l range is 5.82mg/l, variance is 2.72mg/l and standard deviation is 1.65mg/l.The bicarbonate ion has a mean value of 35.65mg/l range is 72mg/l, variance is 392mg/l and standard deviation is 20mg/l.A mean value of 36.7mg/l for total hardness was obtained, range is 54mg/l, variance is 238mg/l and standard deviation is 15.4mg/l.Mean of 35.06mg/l was obtained for Total dissolve solids.(TDS), range of 52.4mg/l, variance of 205mg/l and standard deviation of 14.3mg/l.Which all fall within the recommended standard for potable water World Health Organization (WHO), 2006 Guidelines.
Chemical Analysis: In order to have a more defined and clearer picture of the chemistry of the water under study, the data acquired were further processed using the piper, Durov, Piper and Schoeller semi log diagrams

Piper diagram
The major ionic species in most natural waters are Na, K, Ca, Mg Cl, CO3, HCO3, and SO4.This trilinear diagram showed the percentage composition of three ions.Na and K, the major cations were grouped; there are also three groups of the major anions (Fig. 5).Since all three constituent groups are present, the analyses fell in the interior of the field.The diamondshaped field between the two triangles was then used to represent the composition of water with respect to both cations and anions.The cation point was projected onto the diamond-shaped field parallel to the side of the triangle labeled magnesium and the anion point was similarly projected parallel to the side of the triangle labeled sulfate.
The intersection of the two lines was plotted as a point on the diamond-shaped field.This exercise revealed that the type of water present is calcium, magnesium and bicarbonate types.

Schoeller semilogarithmic Diagram
Schoeller Diagram (Freeze and Cherry, 1979), which was used to verify the results obtained from the Piper diagram, allowed us to make a visual comparison of the compositions of different waters, (Fig. 6).Sodium and Potassium were grouped and the result showed that magnesium is the dominant type followed by calcium and then, bicarbonate.

DISCUSSION
Water quality analyses were carried out on some water samples collected from the study areas.In scope of this study can be divided into three domains.Microbial contamination refers to the presence of disease causing (or pathogene) microbes.Which are generally introduced to water sources by contact with faecal material.Chemical contamination refers to metals, organic compounds and other chemicals that present potential health risk.Physical contamination refers to condition relating to water physical condition, for example colour, odour, temperature and turbidity (cloudiness resulting from the presence of small particles like pieces of soil).
Water Quality analyses for physical parameter showed that the temperature was ambient, the water were colourless, odourless, and tasteless which was within the World Health Organization (WHO, 2006) permissible limit.The major chemical species in most natural waters are Sodium, potassium, magnesium, calcium, chloride, carbonates, bicarbonates and sulphates.For chemical parameters the pH ranged from 5.20 at Ihuowelle Igboukwu to 6.80, at Ebele Achina(highest),total dissolved solids (TDS) from 11.20mg/l at Ezinifite to 71.40mg/l at Achina ,turbidity nil, major cations and anions, calcium (Ca 2+ ) ranged from 5.00mg/l at Okwuchiezeada Ezinifite to 42.00 mg/l at Ndiowu,magnesium (Mg 2+ ) ranged from 0.01mg/l at Uga to 0.18mg/l in Ekwulobia,sulphate was not detected, iron ranged from 0.02mg/l to 0.35mg/l in Igboukwu, Umueze Uga (0.35mg/l), manganese, copper and residual chlorine were not detected whileBicarbonate (HC03) ranged from 7.00mg/l at Ezinifite to 58.00 mg/l at Uga and Sulphate (SO4 2 ) ranged from 0.00mg/l at Igboukwu to 7.00mg/l at Ekwulobia .Bacteriological result showed that total coliform and feacel coliform is zero.The water quality parameters tested fall within the World Health Organization (WHO, 2006) guidelines, desirable, permissible, acceptable limits and Nigeria Standard for Drinking Water Quality (NSDWQ, 2011) apart from the pH values which fall below the World Health Organization standard in some areas, though pH do not pose any health risk in water.The water quality of the groundwater resources in the study area is, therefore described as good.According to the Standard Organization of Nigeria, all water sources intended for human consumption shall comply with Nigeria Standard for Drinking Water Quality (NSDWQ, 2011) as shown in Table 3.
The graphical illustration of the hydrogeochemical analysis carried out using the Piper diagram, Stiff diagram, Shoeller semi logarithm diagram and Durov diagram all showed that "Calcium and Bicarbonate" were the main type of water in the study area and "Magnesium and Bicarbonate" were the additional type water.

Figure 3 :
Figure 3: Drainage and Location Map of the Study Area (Adapted from Abor Map Sheet 300).

Figure 5
Figure 5 Graphical Illustration of Hydrogeochemical Data on the Piper Diagram .

Table 1 :
Statistical Analysis for Major Cations and Anions in Study Areas.

Table 3 :
Nigeria Standard for Drinking Water quality (adopted from Standards Organization of Nigeria, 2007).